You now have the ability to delete purchase orders and sales orders in bulk. Simply choose the POs or SOs that you want to delete and look for the 'Delete' option from the 'Bulk Actions' menu.
The delete is permanent, so you will need to confirm that on the next window that pops up by typing "PERMANENTLY DELETE PURCHASE ORDERS" or "PERMANENTLY DELETE SALES ORDERS" (without the quotation marks) to confirm.
Purchase Orders
Sales Orders